The present invention relates to hand tools for rotating threaded fasteners. More specifically, illustrative embodiments of the present invention relate to wrenches of the type that can be removablely coupled to fasteners and moved alternately through drive and return strokes while remaining attached to the fastener. Movement of a wrench through its drive stroke drives the fastener, but the fastener remains stationary as the wrench moves through its return stroke.
Some wrenches (e.g., socket wrenches) include a fastener engaging mechanism that is rotatably mounted within an opening in an elongated tool body. The fastener engaging mechanism is constructed to be removablely coupled in force-applying relation to a threaded fastener. The fastener engaging mechanism may include a rectangular post to which is coupled a removable socket for engaging the fastener or, alternatively, the fastener engaging mechanism may be in the form of an annular or ring-shaped socket that can be coupled directly to a fastener. The wrench can be moved alternately through drive and return strokes to drive the fastener while remaining coupled to the fastener.
Specifically, when the fastener engaging mechanism is removablely coupled to a threaded fastener and the tool body is rotated in a first rotational direction through a drive stroke, the fastener engaging mechanism rotates with the tool body causing the fastener to rotate. When the tool body is rotated in a second direction opposite the first direction through a return stroke, the fastener engaging mechanism and the fastener remain stationary relative to the tool body. Movement of the tool body again in the driving direction drives the fastener engaging mechanism and the fastener in the first rotational direction. The driving and return directions of the wrench can typically be reversed.
Conventional wrenches of this type include a spring biased pawl mechanism operatively connected between the fastener engaging mechanism and the tool body. Generally, when the tool body is rotated in a driving direction, a pawl of the pawl mechanism pushes against one of a series of teeth on the tool body which rotates the fastener engaging mechanism and the fastener in the driving direction. When the tool body is rotated in a return direction, the pawl mechanism ratchets past the teeth and the fastener engaging mechanism and fastener remain stationary. This type of ratchet mechanism is disadvantageous for several reasons including because the pawl mechanism requires that the tool body be returned through at least a minimum arc length to enable the pawl mechanism to ratchet past at least one ratchet tooth before the tool body is moved again in the driving direction. Wrenches using this type of ratcheting mechanism require a minimum clearance area to allow the wrench to the rotated through the minimum arc length required to cause the pawl tooth to ratchet past at least one tooth and therefore are not usable when this minimal space is not available.
Some wrenches utilize a plurality of pins or rollers operatively connected between the tool body and the fastener engaging mechanism. Examples are disclosed in U.S. Pat. No. 6,276,239 issued to Albertson, U.S. Pat. No. 5,115,699 issued to Mertens and U.S. Pat. No. 6,202,513 issued to Pan. Heretofore, wrenches of this type have had several disadvantages, including, for example, their mechanically complexity and difficulty of manufacturing.
One aspect of the present invention may be embodied in a hand tool for applying torque to a threaded fastener, the hand tool comprising an elongated tool body having a grippable portion at one end portion thereof configured to be gripped by a hand of a worker and having an opening at an opposite end portion thereof defining a rotational axis. A fastener engaging mechanism is rotatably mounted in the opening for bi-directional rotational movement with respect to the tool body about the rotational axis of the opening. The fastener engaging mechanism is configured to be releasably coupled in torque-applying relation to a fastener to which a torque is to be applied. The hand tool includes a driving direction control assembly comprising a cylindrical roller, a spring assembly and a driving direction control switch. The control switch is mounted for movement with respect to the tool body and the fastener engaging mechanism between first and second operative switch positions. The control switch, the spring assembly and the cylindrical roller are constructed and arranged such that (1) when the control switch is in its first operative switch position and the fastener engaging mechanism is releasably coupled to a fastener, the cylindrical roller is positioned such that (a) rotating the tool body about the rotational axis in a first rotational direction forces the cylindrical roller essentially instantaneously into a first wedged relation between surfaces on the tool body and the fastener engaging mechanism, thereby preventing relative rotational movement between the fastener engaging mechanism and the tool body so that rotational movement of the tool body in the first rotational direction rotates the fastener in the first rotational direction and (b) rotating the tool body about the rotational axis in a second rotational direction opposite the first rotational direction moves the cylindrical roller against the biasing of the spring assembly out of the first wedged relation, thereby allowing the tool body to rotate relative to the fastener engaging mechanism and (2) when the control switch is in its second operative switch position and the fastener engaging mechanism releasably coupled to a fastener, the cylindrical roller is positioned such that (a) rotating the tool body about the rotational axis in the second rotational direction forces the cylindrical roller essentially instantaneously into a second wedged relation between surfaces on the tool body and the fastener engaging mechanism, thereby preventing relative rotational movement between the fastener engaging mechanism and the tool body so that rotational movement of the tool body in the second rotational direction rotates the fastener in the second rotational direction and (b) rotating the tool body about the rotational axis in the first rotational direction moves the cylindrical roller against biasing of the spring assembly out of the second wedged relation, thereby allowing the tool body to rotate relative to the fastener engaging mechanism.
Other aspects, features, and advantages of the present invention will become apparent from the following detailed description of the illustrative embodiment, the accompanying drawings, and the appended claims.